HM Defense DefenderM556

The HM Defense DefenderM556 is a full-length 5.56 NATO patrol carbine designed to serve as a reliable, general-issue rifle for law-enforcement agencies. Built around HM Defense’s patented Monobloc barrel technology, the DefenderM556 emphasizes long-term durability, consistency, and ease of maintenance, making it well suited for patrol deployment, training programs, and tactical support roles.

This platform balances accuracy, controllability, and compatibility with standard duty accessories while maintaining a familiar AR-15 manual of arms.

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Operational Advantages for Law Enforcement

 

• Patrol-length configuration ideal for general-issue rifles

• Patented Monobloc barrel system reduces gas system failure points

• Mid-length gas system for smoother recoil and increased component life

• Standard AR-15 controls minimize training and transition time

• Modular handguard supports lights, optics, and accessories

• Duty-grade materials built for high-round-count training cycles

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Barrel System

 

• 16″ 4150 chromoly steel barrel

• Caliber: 5.56 NATO / .223 Remington

• 1:8 twist rate for modern duty ammunition

• Match-grade, button-rifled and honed

• ½×28 threaded muzzle

• Patented Monobloc barrel design with integral gas block

The Monobloc barrel improves alignment and durability by machining the barrel and gas block as a single unit, reducing maintenance and increasing reliability during sustained use.

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Upper & Lower Receivers

 

• Forged 7075-T6 aluminum

• Type III hard-coat anodized finish

• Flat-top Picatinny upper receiver

• Mil-Spec lower receiver for compatibility and serviceability

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Bolt Carrier Group

 

• M16-profile bolt carrier group

• HM Defense patented HMB Bolt, engineered for enhanced strength and extended service life

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Handguard & Accessory Integration

 

• Free-float aluminum handguard

• Full-length Picatinny top rail

• M-LOK mounting surfaces for weapon lights, grips, and accessories

• Optimized length for patrol optics and illumination tools

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Controls & Ergonomics

 

• Mil-Spec fire control group

• Standard AR-15 controls for agency familiarity

• Adjustable stock for body armor and shooter fit

• Enhanced pistol grip

• QD sling-ready end plate

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Weight & Handling

 

• Balanced, patrol-ready configuration

• Designed for prolonged carry, vehicle storage, and rapid deployment

• Reduced recoil impulse improves qualification scores and officer confidence

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Suppressor & Tactical Integration

 

• Threaded barrel supports agency-approved suppressors

• Gas system tuned for reliability with common duty ammunition

• Compatible with night-vision optics, laser aiming devices, and weapon-mounted lights

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Specifications

 

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Agency Use Case Summary

 

The DefenderM556 is well suited for:

• General-issue patrol rifles

• Vehicle-deployed carbines

• Rural and urban patrol environments

• Training and qualification programs

• Tactical support and perimeter roles